The present invention relates to cutting tools including replaceable cutting tips and, more particularly, to such cutting tools with the cutting tips attachable to the cutting tip holders by a threaded connection.
In making threaded connections between two parts, it is possible to permit faster connection of the parts by forming the internal and external threads in a cone or frustoconical shape. In this way, the externally threaded part does not have to be screwed into the internally threaded part from a leading end of the internally threaded part to its final position. Instead, the leading end of the externally threaded part can be inserted into the internally threaded part past internal threads at the leading end of the internally threaded part that define diameters that are larger than the diameter defined by the leading end of the externally threaded part. The leading end of the externally threaded part can be inserted into the internally threaded part up to the point where internal threads begin to contact the external threads. After this point, the externally threaded part is ordinarily turned only a few rotations relative to the internally threaded part before the two parts are in their final relative positions. It is desirable to minimize friction between the internally and externally threaded portions to permit the parts to be quickly turned to their final relative positions.
It is often extremely important in operations such as machining of metal or other workpieces that the location of a cutting edge of a cutting tool be precisely controlled and controllable. Complex machinery is provided to mill, drill, bore, or otherwise perform shaping operations on workpieces by precisely controlling the location of a cutting tool relative to the workpiece. Cutting tools often include replaceable inserts or cutting heads that are attached to permanent toolholders such as shanks that are moved relative to the workpiece.
The accuracy of the mounting of the cutting inserts or heads relative to the toolholder is a factor in the accuracy of the operation to be performed on the workpiece. In the case, for example, of a rotating tool, an insert or tool head that is displaced axially relative to a rotating shank to which it is attached can damage the workpiece and may necessitate the rejection of an expensive part. It is therefore desirable to minimize the possibility of movement of an insert or tool head relative to a toolholder. In many tools, threaded connections or portions of threaded connections form axial and/or radial supports or part of a radial and/or axial supporting arrangement for radially and/or axially supporting and positioning a tool head relative to a toolholder. Often, during cutting operations, substantial radial and axial forces are applied to threaded connections between a tool head and a toolholder, which can damage the threads.
In accordance with an aspect of the present invention, a cutting tip includes a working end portion disposed along an axis of the cutting tip and including one or more cutting edges for machining a workpiece, and a mounting portion disposed along the axis of the cutting tip and including a frustoconical supporting surface tip portion and a frustoconical threaded portion.
In accordance with another aspect of the present invention, a cutting tool includes a replaceable cutting tip including a working end portion disposed along an axis of the cutting tip and including one or more cutting edges for machining a workpiece, and a mounting portion disposed along the axis of the cutting tool and including a frustoconical supporting surface tip portion and a frustoconical threaded tip portion. The cutting tool also includes a cutting tip holder, the holder including a holder mounting portion including a frustoconical abutment surface holder portion for abutting the frustoconical supporting surface tip portion to position the cutting tip axially and radially in an operating position relative to the cutting tip holder and a frustoconical threaded holder portion for mating with the frustoconical threaded tip portion.